Many years ago I graduated university with a major in mathematics and I used to think I was pretty good at picking up new maths including pretty advanced stuff like calculus of variations and fourier analysis but for some reason I'm having a real hard time getting into quantum mechanics and Hamiltonians and all that. Am I getting old? Just out of practice? It annoys me...
Have you studied Analytical Mechanics first? Sakurai is a very good book for QM.
If you don't get it physically first then the feynman lectures are very good - physics is more than postulates and proof, at very least there's less to memorise if you start from the bottom.
